Even if you go to a bank branch, large withdrawals ($100k+) need to be announced days in advance, they will not give you the money on the spot.
Making matters worse, cryptocurrency is not a bank branch. Large transactions can happen on-chain without announcing anything to anyone, the bottleneck only hits once you try liquidating funds you don't own. Maybe you're right, and FTX has fallen on some bad times. Whatever the case may be, this is entirely their problem and one of many hundred issues that crop up when you create custodial crypto systems. I hope they continue to fail and remind everyone how P2P currency is meant to be distributed.
If business is going as usual, customers don't see anything, because hot wallet funds are kept at acceptable levels. Not too high, because you don't want to have too much funds online in a case a hack happens. Not too low, because you want customer withdrawals to function. However, if some kind of panic happens and people start withdrawing a lot at once, then you will always have delays, assuming that you have a sane system.
Hint: if it's more than 1 block (~10mins) you're either incompetent or fraudulent
Exchanges simply don't work. The comparison between them and banks ignores the surrounding regulation and guarantees that banks are obligated to issue you. Are my FTX holdings FDIC insured?
It's not that simple. Operate enough against the user's and you'll find yourself indicted. Not being regulated doesn't mean it's a free for all and you can just take the money.
Exchanges arose because pure P2P currency distribution is impractical. Crypto's assumptions about whether, how, and why currency should be decentralized are fundamentally at odds with human behavior.
This is closer to you writing a check and it bouncing not because you don't have enough money in your account but because your bank doesn't have enough money to settle the transaction.